This invention relates to a tone signal generation device of a waveshape memory reading type and, more particularly, to a tone signal generation device capable of generating a high-quality tone signal by accessing a waveshape memory storing a full or partial waveshape in plural periods from the start of sounding of a tone to the end thereof.
Known in the art is a tone signal generation device capable of generating a high-quality tone simulating closely a tone of a natural musical instrument by storing a full or partial waveshape in plural periods from the start of sounding of a tone to the end thereof in a waveshape memory and accessing this waveshape memory (e.g., U.S. Pat. No. 4,383,462).
Since this prior art tone generation device reads out a full waveshape or a partial waveshape stored in the waveshape memory and provides the read out waveshape directly as a tone signal, a tone color change of a generated tone tends to lack in variation and therefore leaves something to be improved musically. If, in order to improve this defect, the tone generation device is provided with a key scaling control in which a tone color is changed in accordance with a tone pitch or a tone range of a tone to be generated, a touch response control in which the tone color is changed in accordance with an operating manner of a playing key such as a depression speed and a depression strength, and an operator control in which the tone colors are changed in accordance with an operation manner of various control knobs, a plurality of waveshape memories must be provided and one of them must be selected for reading for effecting these controls with a resulting complicated construction of the device and requirement for a tremendous memory capacity of the waveshape memories.
Besides, since a waveshape memory stores a waveshape of plural periods even in a case where the tone color change is not imparted to a tone, the memory capacity of the waveshape memory tends to become large for this reason only. If a low sampling frequency is used with a resulting reduction in the sampling number, the memory capacity accordingly is reduced. This, however, eliminates harmonic components in a high frequency range so that the quality of a tone obtained will be deteriorated.
The present invention, therefore, aims to solve the problem in the tone signal generation device generating a high-quality tone signal that the attempt for introducing a tone color change control such as the key scaling control is inevitably accompanied by a complicated construction of the device and the problem that the waveshape memory requires a tremendous amount of memory capacity.
It is an object of the invention to provide a tone signal generation device capable of imparting the tone color change such as the key scaling with a simple construction using a waveshape memory of a relatively small capacity.
It is another object of the invention to provide a tone generation device capable of generating a tone signal using a waveshape memory of a relatively small capacity without substantially lowering the quality of the generated tone.